Nanocomposites prove efficient in improving mechanical properties of rubber

Iranian researchers from Qom University of Technology succeeded in increasing the thermal resistant (lifetime) of ethylene propylene diene monomer (EPDM) rubber and improving its mechanical properties by using zinc oxide nanoparticles in annealing of the rubber. This research studied the effect of using zinc oxide nanoparticles in the annealing system of EPDM on the lifetime of the rubber and on the amount of mechanical changes in the elastomer. By precisely analyzing the morphology, the researchers obtained appropriate size distribution of zinc oxide nanoparticles to control the annealing system. In the next stage, they studied the improvement in thermal resistant of the rubber, which included activation energy and reaction degree of the degradation, by using Friedman and Kissinger kinetics models based on TGA-DTA thermal tests. Finally, they compared mechanical properties of the nanocomposite, including roughness, resilience and mechanodynamic tests, with other common annealing systems. Results of the research showed that thermal resistance against degradation and lifetime increase occur when an increase of approximately 200% takes place in the activation energy of EPDM degradation reaction. The increase in lifetime is a result of homogenization of elastomer annealing system in the presence of zinc oxide nanoparticles with desirable specific area. An increase of about 10-30% was observed in abrasion resistance, resilience, and roughness depending on the volume ratio of zinc oxide nanoparticles used in the rubber. The lifetime of a commonly-used elastomer increases by introducing this new improved annealing method at nanometric scale, which is based on the design of a nanocomposite polymer. Consequently, environmental pollution decreases since a non-degradable rubber often does not require to be replaced by another piece. Results of the research have been published in details in Journal of Analysis and Calorimetry, vol. 110, issue 3, December 2012, pp. 1407-1414.